@henningw - maybe you didn't understand, but there was no fix for libressl, so your remark "If you observe another crash with libressl,..." is pointless, the crash reported initially in this issue is still there, nothing to wait for something else.
But libressl has diverged quite a lot from openssl -- I looked a bit like 2 years ago or so and iirc, they do not allow setting custom memory manager. That makes this case like implementing a new module, something similar to implemeting a tls module using gnutls. From this perspective, it is not a bug, it can be eventually a feature request. The request for gnutls was moved to wiki, this can be added there if someone wants to implement at some point:
* https://www.kamailio.org/wiki/devel/new-features-requests
Otherwise, to my rather limited knowledge about that OS, one can still install openssl on openbsd, so that should be the choice of use.